Conventional greenhouses consist of ground-standing transparent shell buildings designed for inter alia growing plants in unfavorable weather conditions, while still providing natural light to the plants. These simple greenhouses are acceptable in countries where the climate is normally mild and temperatures moderate; however, they are unsatisfactory in harsher climates, because of temperature control problems, light intensity and, most importantly, control of evaporation/watering of the plants. Of course, one can build opaque, insulated greenhouses to eliminate these problems, where light must be artificially produced; but then, the cost factor becomes a major consideration.
In the prior art, improved greenhouses have been proposed, to counter at least some of the above problems. For exemple, in U.S. Pat. No. 3,315,409, issued in 1967 to Poulin, there is disclosed a greenhouse for growing plants, including two semi-spherical transparent shells 1-2 and a well 4 at the apex thereof. The well 4 is provided with float valves 3, closing circular perforations 4.31 pierced therein. Water deposited by rain in the wall 4 is admitted into the greenhouse when the water level rises sufficiently in the well to buoy the float valves 3, so as to water plants therebelow. It also includes heat evacuation means 5, about well 4.
This watering means 3-4 of Poulin is operative only in areas where rainfalls are substantial and occur regularly and, accordingly, would not be suitable for desertic regions where rainfalls are extremely scarce. Moreover, because the shells 1-2 are both transparent, the plants grown in the greenhouse will have to be limited in their variety, since a great number of plant species cannot withstand the high level of illumination and/or heat (not-withstanding heat evacuation means 5, which does not induce air circulation in the greenhouse) generated by sunrays in desertic countries.
None of the known prior art greenhouses meet the challenge of being adapted to grow plants in desertic or at least semi-arid regions.